And I don't mean that steady ache in your shoulders from hovering over the keyboard. ;)
Tense is probably one of the first decisions you need to make when you sit down and start writing a new project. Past or present? This also ties right into your point of view (POV).
Let's start with a basic look at each, the way I see them. (Which is not to say it's correct, it's just how I imagine it in my own little world over here.)
Past tense is telling a story that already happened, a recounting of events. So, your narrator's position is later down the line, they already know how the story ends, and what is going to happen next.
Present tense is telling a story as it happens. Nobody knows more than the character who's head you're in at that very moment. Your narrator knows the past, but has no idea what's to come.
So, the first thing you have to decide is how immediate your story is. To pull off a present tense story effectively there seems to be a fine line between being fast enough paced to keep your audience engaged, and being so fast paced that you exhaust them.
On the other side of the coin, with past tense it gives you a little more distance between the story and the audience, so (to me) it gives you more room for a faster pace and a more intense story (Like a thriller or horror story. I could not imagine reading a horror story in first person, present tense. That would just be too intense for me.).
I've written in both, and they both have their challenges. With HAPPILY NEVER AFTER I really found my stride in present tense. I don't know if that will carry forward with my next project or yet, I can't seem to decide. ;) But I think it's definitely something to decide on a project to project basis anyway.
What about you all? Have you written in both tenses, or do you prefer one over the other?